This fantastic, big-eyed little alien — I really cannot overemphasize how funky this thing looks — is a dusky-winged hover fly, Ocyptamus fuscipennis, a harmless little syrphid fly.
I tried to find something else to say about this species, but it’s another Wikipedia stub. Trying to describe “syrphid flies” as a whole gives me so many species (about 6,000) that there aren’t really any umbrella statements that can be made. Syrphid flies are also called flower flies (since many of them feed on flowers) and hover flies (since many of them can hover in mid-air). Many of them are yellow and black striped and/or otherwise mimickers of bees/wasps.
The larvae are voracious predators of aphids. This is an Ocyptamus sp. larva devouring an aphid: